In 1970, Congress passed the Clean Air Act and established the Environmental Protection Agency (EPA) which initiated a series of graduated emission standards and requirements for maintenance of vehicles over extended periods of time. In the beginning there were few standards, however, in 1988, the Society of Automotive Engineers (SAE) developed a set of diagnostic test signals, and the EPA adapted most of the SAE standards for On-Board Diagnostic programs and recommendations (OBD). Currently, the second generation of these diagnostic standards (OBD-II) have been adopted by the EPA and, as such, internal combustion engine vehicles must now meet the federally mandated OBD-II standards for the life of the vehicle.
A main focus of the EPA in regard to internal combustion engines is on the emissions of the engines. To meet the current federally mandated emission standards prescribed by OBD-II, an internal combustion engine requires management of air flow through an intake manifold. In addition, regulatory requirements mandate that the components used to ensure compliance of the emission standards be continuously monitored over the life of the vehicle. This is in an effort to ensure that the emissions performance over the useful life of the vehicle is not degraded due to a component or system malfunction. For the air intake manifold, one device used in some engines to obtain improved emissions and engine performance is an intake manifold tuning valve which can be used to join intake manifold plenums at a certain range of engine speeds. Generally, the actuators used to control the intake manifold tuning valves (herein referred to as IMTV actuators) have been constructed as two position actuators, having a fully open position and a fully closed position. In addition, the actuators generally do not provide position feedback capability to indicate which position the actuator is in. This two position operation of the IMTV actuator limits its ability to regulate the air flow through the intake manifold, and thus, can restrict the ability of the engine to operate at its a maximum performance level and can limit the ability of the engine to meet emissions and fuel economy goals.
The OBD-II regulations require that the presence and functionality of emission systems components be monitored. Generally, the monitoring function may be performed using one or more external sensors connected to the vehicle engine controller. This approach adds to the complexity of the emission system assembly, for example by adding additional components and wire connections. In addition, the added external components increase the amount of communication and analysis burden on the engine controller. Though the current OBD-II emission control system requirements come at an increased cost, the manufacturer has little option but to take on these expenses, as a result of having to meet the federally mandated standards.